DESCRIPTION: (Applicant's Description) It is our intent here to lay the groundwork for a translational study of the efficacy of NIR optical method in deternining the level of hypoxia in human breast cancer by NIR optical spectroscopy and imaging. The test requires a gold standard of breast tumor hypoxia which is to be provided by pO2 deterninations where the instrumentation, expertise and technology is available at the Leipzig University while the expertise and technology for NIR spectroscopy and imaging is available at the University of Pennsylvania affording an opportunity for translational research. It is our intent to mobilize activities at these two locations in order that a initial test of 50 breast cancers can be made to validate that the spectroscopy and imaging of breast tumor hypoxia gives values comparable to those obtained with the gold standard of pO2 determination and that the tumor localization is consistent with other modalities particularly ultrasound, mammography and biopsy. Thus these studies require validation that these two groups can work together; the Philadelphia group providing instrumentation and personnel skilled in use of the instrumentation, whilst the Leipzig group will provide not only expertise in pO2 determination, ultrasound, biopsy, marnnography, but also the capability of making available a large population of high risk breast cancer patients who are willing to accept the complete protocol for breast cancer examinations. It is our intent to provide two types of NIR information: I) localized and quantitative spectroscopy of the desaturation of hemoglobin and the blood content in the same breast canceri region as that in which the pO2 deternination takes place. 2) A NIR imaging system which gives rapid and effective imaging of the deoxygenation of hemoglobin and blood concentration relative to nearby normal breast tissue. While the pO2 determinations and NIR hemoglobin spectroscopy and imaging currently afford the basis for calibration in models, the comparative study has never been done before in human breast cancers. If ourintended goals of demonstrating feasibility are achieved, then application for support through regular RO1channels would appear to be justified.